Toolholder



Jan. 2, 1951 E. R. KooNz TOOLHOLDER Filed Feb. 5, 1947 Y INVE'NWR.

TTURN'Y Patented Jan. 2, 1951 UNITED STATES y,

reN'r orifice (Cl, 27th-569i 2 Claims. l

This invention relates to improvements in chucks for dies, die adapters, hollow mills and similar tools which are held in a chuck during use.

An object of this invention is to provide for the gripping of the' tool in place onits chuck in the absence of, or before the fastening on of, a retaining cap.

A further object of the invention is the provision of convenient, unobtrusive and durable meansV for holding the tool on the chuck in the absence of a retaining cap and a minimum of stress and wear of the holding means during the operation of the tool.

Other objects including the particular construction, arrangement and combination of parts Will appear from the following description taken together with the drawings in which:

Fig. l is a longitudinal central section of a die held on a chuck;

Fig. 2 is an end view of the die on the chuck showing the cap and die partially in section;

Fig. 3 is a plan view of the die and chuck showing the cap and die in section and the head partially in section; and

Fig. 4 is an enlarged section of portions of the die and chuck at a point of contact.

As shown in Fig. 1 the invention is applied to a holder for .a die. A threading device is shown comprising a threading die In seating against a chuck II and held by a cap I2 fastened to the chuck I I and having an upper annular portion I3 with a tapered bore I4 which embraces lands I5 of the die I0. Cap I2 is fastened to the chuck II by internal threads I1 on the cap I2 which engages a threaded portion I8 of the chuck II. By turning the cap I2 on the threaded portion I8 the annular portion I3 presses the die I9 onto its seat on the chuck II.

The chuck II comprises a body I9 having a head 2l on which the threaded portion I3 is formed. The body I9 extends into and slides longitudinally in a tubular shank 22. A spring 23 held in compression between a collar 24 and a restricted portion 26 of the shank 22 tends to retain the body I9 within the shank 22. The end of head 2I at 2l forming a ring as shown in Fig. 2 is ground to a finish and provided with tongues 28. The die I0 rests against the end 21 and grooves 2S in the base of the die I3 receive the tongues 28. The tongues 28 and grooves 29 are machined to provide a clearance 31 between the sides of the tongues 28 and the grooves 23. Thus, the t of the grooves 29 on the tongues 28 is loose permitting play between the die I3 and the chuck I I. i

The tongues 28 divide the end surface 21 into two symmetrical sectors 33 and 3|. In each of the sectors 33 and 3| the head 2i has channels 32 to receive gripping members 33 which. are diametrically positioned on the head 2i. As shown in the plan view of Fig'. 3 each gripping member 33 is a long flat piece of' resilient metal extending from the back of the threaded portion I8- o'ut over the'y end 2i and engaging the cylindricai surface 35 of lower portion 3:4" of the die l t. TheA members 33 seat in the channelsY 32 and are tightly fastened at the rear end or away from the die by machine screws The channels 32' are cut in the head 2| so that the minimum dimension a in Fig. l between the opposed channels is less than the over-all diameter of the lower portion of the die I9 when the die I0 is seated on the end 2l, the lower portion 35 ts tightly between members 33 and between the tongues 28 and the members 33. As shown in Fig. 4 the ilat member 33 forms a tangential contact with the surface 35 at 33 and the curvature of the cylindrical surface 35 provides clearances 39 between the member 33 and the surface 35.

In operation when a die is to be replaced on the chuck I I the retaining cap .I2 is removed and the die to be replaced is removed. The new die is then positioned on the end 2l. The members 33 spread slightly to receive the slightly larger lower portion 34 of the die and because of the resilience of the members 33 they hold the die in place on the end 2l until the retaining cap has been screwed into position with the annular portion I3 bearing against the lands L of the die Ill. The die I though held snugly between the members 33 is easily inserted because of the clearances 33 provided on each side of the areas of contact 38 between the members 33 and the surface 35. The clearances 39 permit the die I@ to slip into position on the surface 21 and not catch on the edges of the members 33.

The chuck and die are then ready for the cutting operation intended and the retaining cap I2 takes up the thrust on the die I9 during the cutting operation. Thus, the members 331 are not subject to stress and wear during the cutting operation and the only wear and stress that the members 33 are subjected to is the rubbing against the lower portion 34 and the slight ilexing of the members 33 which occur during the removal and replacement of the die on the end 21. Consequently, the wear between the members 33 and the dies I9 is extremely small. Also the displacement of the resilient member 33 by placing a die I9 on the end 2'! is small in comparison with the overall length of the member 33 and con- 3 sequently the strain of the flexing of the member 33 is slight.

When a die is being replaced on a chuck it is of advantage to avoid the inconvenience and delay cause by the recovery and replacement of the die falling from the chuck after being placed in position and before the screwing on of the retaining cap. Also with the members 33 of this invention a die or other tool 'may be placed in position on a chuck in which the end 2T is pointed downward. Another advantage derived from this invention is the elimination of the necessity of holding the die or other tool in place on a tilted end of the chuck While the retaining cap is being screwed into position.

While the described arrangement has referred particularly to holding a die in a chuck it willV be apparent that the features may be applied to a chuck holding other tools without departing from the scope of the invention as set forth in the claims.

Y I claim:

1. In a tool chuck a shank having a threaded head portion with an annular end surface for receiving a transversely grooved end surface of a generally cylindrical tool and having alined projections adapted to t endwise into the groove in said tool, a pair of oppositely positioned longitudinal channels in the threaded periphery of said head portion evenly spaced between said projections, gripping members fastened in said channels and having ends protruding outward 4 from said annular end surface and spaced apart a distance less than the diameter of the tool so as to be engagedrand slightly flexed by the periphery of said tool as it is slid sidewise over said projections, and a cap threaded on said head surrounding said gripping members and adapted to engage said tool and adjust it to a precisely centered seat on said annular end surface with corresponding flexure of said gripping members in the iinal set position of the tool in the chuck. 2. A tool chuck as set forth in claim 1 in which the bottoms of the channels are transversely spaced apart a distance less than the over-all diameter of the portion of the tool engaged by said gripping members.

EARL R. KOONZ.

REFERENCES CITED The following references are of -record in the 

